<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
 .outerDiv {
            width: 800px;
            height: 300px;
            border: 1px solid green;
            background-color: rgb(230, 224, 224);
            /* margin: auto auto; */
            margin: auto auto;
        }
        .innerDiv{
            width: 100px;
            height: 100px;
            border: 1px solid blue;
            float: left;
            /* margin-top: 10px;
            margin-right: 20px;
            margin-bottom: 30px;
            margin-left: 40px; */
            /* margin: 10px 20px 30px 40px; */
        }
        .di{
            background-color: rgb(148, 214, 49);
       margin-right: 20px;
       margin-left: 30px;
       margin-top: 20px;
       padding: 10px 20px 30px 40px;
        }
        .d2{
            background-color: rgb(112, 12, 12);   
            margin-left: 20px;
            margin-top: 20px;
            margin-right: 20px;
            padding: 10px 20px 30px 40px;
           
        }
        .d3{
            background-color: rgb(142, 236, 229);
            /* margin-left: 20px; */
            margin:  auto;
        }
</style>
   

<body>
    <div class="outerDiv">
        <div class="innerDiv d1">框1</div>
        <div class="innerDiv d2">框2</div>
        <div class="innerDiv d3">框3</div>
   </div> 
    
</body>
</html>